1. Field of the Invention
The invention is generally related to a method for light compensation and an apparatus using the method. More particularly, the invention is related to a method for compensating light reflection of a projection frame and a projection apparatus.
2. Description of Related Art
Due to advancements in projection technologies, development of projection systems and related equipments has leapt forward significantly in recent years. The principles of a projector are similar to an overhead projector or a slide projector. In these systems, a bulb with high brightness is used as a light source to project an image onto a white screen or wall. Nowadays, commercially available projectors can be categorized into CRT projectors, transmissive polysilicon projectors (commonly referred to as LCD projectors), and Digital Light Processing (DLP) projectors.
The LCD projectors can be produced to be thin while possessing a small footprint. In addition, all images are projected from the same lens and there is no need to joint these images. Therefore, compared to the traditional projectors, the LCD projectors have become a mainstream on the market due to features of convenient to carry and easy to adjust. Moreover, when presenting a report or a training course, the projector can be connected to a computer, so as to directly project the images in the computer onto a screen, thus saving the need to produce slides and making progress towards a paperless office.
However, in light of how projectors are used nowadays, an ideal situation is to project frames on a white and fully reflective screen, while surrounding light sources are turned off or shielded. Practically, the projection frames are affected by various types of light pollution (e.g., from a fluorescent lamp) causing a decrease in contrast as well as shifts in color temperature. If the projected background is not a white screen or wall, reduction in reflectivity also causes the decrease in contrast and the shifts in hues. Therefore, there is a need to develop a projection apparatus capable of adjusting the quality of projected images according to environmental changes, thereby providing users with a desirable viewing quality.